mm: make the vma list be doubly linked
[linux-2.6.git] / mm / mmap.c
1 /*
2  * mm/mmap.c
3  *
4  * Written by obz.
5  *
6  * Address space accounting code        <alan@lxorguk.ukuu.org.uk>
7  */
8
9 #include <linux/slab.h>
10 #include <linux/backing-dev.h>
11 #include <linux/mm.h>
12 #include <linux/shm.h>
13 #include <linux/mman.h>
14 #include <linux/pagemap.h>
15 #include <linux/swap.h>
16 #include <linux/syscalls.h>
17 #include <linux/capability.h>
18 #include <linux/init.h>
19 #include <linux/file.h>
20 #include <linux/fs.h>
21 #include <linux/personality.h>
22 #include <linux/security.h>
23 #include <linux/hugetlb.h>
24 #include <linux/profile.h>
25 #include <linux/module.h>
26 #include <linux/mount.h>
27 #include <linux/mempolicy.h>
28 #include <linux/rmap.h>
29 #include <linux/mmu_notifier.h>
30 #include <linux/perf_event.h>
31
32 #include <asm/uaccess.h>
33 #include <asm/cacheflush.h>
34 #include <asm/tlb.h>
35 #include <asm/mmu_context.h>
36
37 #include "internal.h"
38
39 #ifndef arch_mmap_check
40 #define arch_mmap_check(addr, len, flags)       (0)
41 #endif
42
43 #ifndef arch_rebalance_pgtables
44 #define arch_rebalance_pgtables(addr, len)              (addr)
45 #endif
46
47 static void unmap_region(struct mm_struct *mm,
48                 struct vm_area_struct *vma, struct vm_area_struct *prev,
49                 unsigned long start, unsigned long end);
50
51 /*
52  * WARNING: the debugging will use recursive algorithms so never enable this
53  * unless you know what you are doing.
54  */
55 #undef DEBUG_MM_RB
56
57 /* description of effects of mapping type and prot in current implementation.
58  * this is due to the limited x86 page protection hardware.  The expected
59  * behavior is in parens:
60  *
61  * map_type     prot
62  *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
63  * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
64  *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
65  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
66  *              
67  * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
68  *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
69  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
70  *
71  */
72 pgprot_t protection_map[16] = {
73         __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
74         __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
75 };
76
77 pgprot_t vm_get_page_prot(unsigned long vm_flags)
78 {
79         return __pgprot(pgprot_val(protection_map[vm_flags &
80                                 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
81                         pgprot_val(arch_vm_get_page_prot(vm_flags)));
82 }
83 EXPORT_SYMBOL(vm_get_page_prot);
84
85 int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
86 int sysctl_overcommit_ratio = 50;       /* default is 50% */
87 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
88 struct percpu_counter vm_committed_as;
89
90 /*
91  * Check that a process has enough memory to allocate a new virtual
92  * mapping. 0 means there is enough memory for the allocation to
93  * succeed and -ENOMEM implies there is not.
94  *
95  * We currently support three overcommit policies, which are set via the
96  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
97  *
98  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
99  * Additional code 2002 Jul 20 by Robert Love.
100  *
101  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
102  *
103  * Note this is a helper function intended to be used by LSMs which
104  * wish to use this logic.
105  */
106 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
107 {
108         unsigned long free, allowed;
109
110         vm_acct_memory(pages);
111
112         /*
113          * Sometimes we want to use more memory than we have
114          */
115         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
116                 return 0;
117
118         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
119                 unsigned long n;
120
121                 free = global_page_state(NR_FILE_PAGES);
122                 free += nr_swap_pages;
123
124                 /*
125                  * Any slabs which are created with the
126                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
127                  * which are reclaimable, under pressure.  The dentry
128                  * cache and most inode caches should fall into this
129                  */
130                 free += global_page_state(NR_SLAB_RECLAIMABLE);
131
132                 /*
133                  * Leave the last 3% for root
134                  */
135                 if (!cap_sys_admin)
136                         free -= free / 32;
137
138                 if (free > pages)
139                         return 0;
140
141                 /*
142                  * nr_free_pages() is very expensive on large systems,
143                  * only call if we're about to fail.
144                  */
145                 n = nr_free_pages();
146
147                 /*
148                  * Leave reserved pages. The pages are not for anonymous pages.
149                  */
150                 if (n <= totalreserve_pages)
151                         goto error;
152                 else
153                         n -= totalreserve_pages;
154
155                 /*
156                  * Leave the last 3% for root
157                  */
158                 if (!cap_sys_admin)
159                         n -= n / 32;
160                 free += n;
161
162                 if (free > pages)
163                         return 0;
164
165                 goto error;
166         }
167
168         allowed = (totalram_pages - hugetlb_total_pages())
169                 * sysctl_overcommit_ratio / 100;
170         /*
171          * Leave the last 3% for root
172          */
173         if (!cap_sys_admin)
174                 allowed -= allowed / 32;
175         allowed += total_swap_pages;
176
177         /* Don't let a single process grow too big:
178            leave 3% of the size of this process for other processes */
179         if (mm)
180                 allowed -= mm->total_vm / 32;
181
182         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
183                 return 0;
184 error:
185         vm_unacct_memory(pages);
186
187         return -ENOMEM;
188 }
189
190 /*
191  * Requires inode->i_mapping->i_mmap_lock
192  */
193 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
194                 struct file *file, struct address_space *mapping)
195 {
196         if (vma->vm_flags & VM_DENYWRITE)
197                 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
198         if (vma->vm_flags & VM_SHARED)
199                 mapping->i_mmap_writable--;
200
201         flush_dcache_mmap_lock(mapping);
202         if (unlikely(vma->vm_flags & VM_NONLINEAR))
203                 list_del_init(&vma->shared.vm_set.list);
204         else
205                 vma_prio_tree_remove(vma, &mapping->i_mmap);
206         flush_dcache_mmap_unlock(mapping);
207 }
208
209 /*
210  * Unlink a file-based vm structure from its prio_tree, to hide
211  * vma from rmap and vmtruncate before freeing its page tables.
212  */
213 void unlink_file_vma(struct vm_area_struct *vma)
214 {
215         struct file *file = vma->vm_file;
216
217         if (file) {
218                 struct address_space *mapping = file->f_mapping;
219                 spin_lock(&mapping->i_mmap_lock);
220                 __remove_shared_vm_struct(vma, file, mapping);
221                 spin_unlock(&mapping->i_mmap_lock);
222         }
223 }
224
225 /*
226  * Close a vm structure and free it, returning the next.
227  */
228 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
229 {
230         struct vm_area_struct *next = vma->vm_next;
231
232         might_sleep();
233         if (vma->vm_ops && vma->vm_ops->close)
234                 vma->vm_ops->close(vma);
235         if (vma->vm_file) {
236                 fput(vma->vm_file);
237                 if (vma->vm_flags & VM_EXECUTABLE)
238                         removed_exe_file_vma(vma->vm_mm);
239         }
240         mpol_put(vma_policy(vma));
241         kmem_cache_free(vm_area_cachep, vma);
242         return next;
243 }
244
245 SYSCALL_DEFINE1(brk, unsigned long, brk)
246 {
247         unsigned long rlim, retval;
248         unsigned long newbrk, oldbrk;
249         struct mm_struct *mm = current->mm;
250         unsigned long min_brk;
251
252         down_write(&mm->mmap_sem);
253
254 #ifdef CONFIG_COMPAT_BRK
255         min_brk = mm->end_code;
256 #else
257         min_brk = mm->start_brk;
258 #endif
259         if (brk < min_brk)
260                 goto out;
261
262         /*
263          * Check against rlimit here. If this check is done later after the test
264          * of oldbrk with newbrk then it can escape the test and let the data
265          * segment grow beyond its set limit the in case where the limit is
266          * not page aligned -Ram Gupta
267          */
268         rlim = rlimit(RLIMIT_DATA);
269         if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
270                         (mm->end_data - mm->start_data) > rlim)
271                 goto out;
272
273         newbrk = PAGE_ALIGN(brk);
274         oldbrk = PAGE_ALIGN(mm->brk);
275         if (oldbrk == newbrk)
276                 goto set_brk;
277
278         /* Always allow shrinking brk. */
279         if (brk <= mm->brk) {
280                 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
281                         goto set_brk;
282                 goto out;
283         }
284
285         /* Check against existing mmap mappings. */
286         if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
287                 goto out;
288
289         /* Ok, looks good - let it rip. */
290         if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
291                 goto out;
292 set_brk:
293         mm->brk = brk;
294 out:
295         retval = mm->brk;
296         up_write(&mm->mmap_sem);
297         return retval;
298 }
299
300 #ifdef DEBUG_MM_RB
301 static int browse_rb(struct rb_root *root)
302 {
303         int i = 0, j;
304         struct rb_node *nd, *pn = NULL;
305         unsigned long prev = 0, pend = 0;
306
307         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
308                 struct vm_area_struct *vma;
309                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
310                 if (vma->vm_start < prev)
311                         printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
312                 if (vma->vm_start < pend)
313                         printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
314                 if (vma->vm_start > vma->vm_end)
315                         printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
316                 i++;
317                 pn = nd;
318                 prev = vma->vm_start;
319                 pend = vma->vm_end;
320         }
321         j = 0;
322         for (nd = pn; nd; nd = rb_prev(nd)) {
323                 j++;
324         }
325         if (i != j)
326                 printk("backwards %d, forwards %d\n", j, i), i = 0;
327         return i;
328 }
329
330 void validate_mm(struct mm_struct *mm)
331 {
332         int bug = 0;
333         int i = 0;
334         struct vm_area_struct *tmp = mm->mmap;
335         while (tmp) {
336                 tmp = tmp->vm_next;
337                 i++;
338         }
339         if (i != mm->map_count)
340                 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
341         i = browse_rb(&mm->mm_rb);
342         if (i != mm->map_count)
343                 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
344         BUG_ON(bug);
345 }
346 #else
347 #define validate_mm(mm) do { } while (0)
348 #endif
349
350 static struct vm_area_struct *
351 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
352                 struct vm_area_struct **pprev, struct rb_node ***rb_link,
353                 struct rb_node ** rb_parent)
354 {
355         struct vm_area_struct * vma;
356         struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
357
358         __rb_link = &mm->mm_rb.rb_node;
359         rb_prev = __rb_parent = NULL;
360         vma = NULL;
361
362         while (*__rb_link) {
363                 struct vm_area_struct *vma_tmp;
364
365                 __rb_parent = *__rb_link;
366                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
367
368                 if (vma_tmp->vm_end > addr) {
369                         vma = vma_tmp;
370                         if (vma_tmp->vm_start <= addr)
371                                 break;
372                         __rb_link = &__rb_parent->rb_left;
373                 } else {
374                         rb_prev = __rb_parent;
375                         __rb_link = &__rb_parent->rb_right;
376                 }
377         }
378
379         *pprev = NULL;
380         if (rb_prev)
381                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
382         *rb_link = __rb_link;
383         *rb_parent = __rb_parent;
384         return vma;
385 }
386
387 static inline void
388 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
389                 struct vm_area_struct *prev, struct rb_node *rb_parent)
390 {
391         struct vm_area_struct *next;
392
393         vma->vm_prev = prev;
394         if (prev) {
395                 next = prev->vm_next;
396                 prev->vm_next = vma;
397         } else {
398                 mm->mmap = vma;
399                 if (rb_parent)
400                         next = rb_entry(rb_parent,
401                                         struct vm_area_struct, vm_rb);
402                 else
403                         next = NULL;
404         }
405         vma->vm_next = next;
406         if (next)
407                 next->vm_prev = vma;
408 }
409
410 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
411                 struct rb_node **rb_link, struct rb_node *rb_parent)
412 {
413         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
414         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
415 }
416
417 static void __vma_link_file(struct vm_area_struct *vma)
418 {
419         struct file *file;
420
421         file = vma->vm_file;
422         if (file) {
423                 struct address_space *mapping = file->f_mapping;
424
425                 if (vma->vm_flags & VM_DENYWRITE)
426                         atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
427                 if (vma->vm_flags & VM_SHARED)
428                         mapping->i_mmap_writable++;
429
430                 flush_dcache_mmap_lock(mapping);
431                 if (unlikely(vma->vm_flags & VM_NONLINEAR))
432                         vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
433                 else
434                         vma_prio_tree_insert(vma, &mapping->i_mmap);
435                 flush_dcache_mmap_unlock(mapping);
436         }
437 }
438
439 static void
440 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
441         struct vm_area_struct *prev, struct rb_node **rb_link,
442         struct rb_node *rb_parent)
443 {
444         __vma_link_list(mm, vma, prev, rb_parent);
445         __vma_link_rb(mm, vma, rb_link, rb_parent);
446 }
447
448 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
449                         struct vm_area_struct *prev, struct rb_node **rb_link,
450                         struct rb_node *rb_parent)
451 {
452         struct address_space *mapping = NULL;
453
454         if (vma->vm_file)
455                 mapping = vma->vm_file->f_mapping;
456
457         if (mapping) {
458                 spin_lock(&mapping->i_mmap_lock);
459                 vma->vm_truncate_count = mapping->truncate_count;
460         }
461
462         __vma_link(mm, vma, prev, rb_link, rb_parent);
463         __vma_link_file(vma);
464
465         if (mapping)
466                 spin_unlock(&mapping->i_mmap_lock);
467
468         mm->map_count++;
469         validate_mm(mm);
470 }
471
472 /*
473  * Helper for vma_adjust in the split_vma insert case:
474  * insert vm structure into list and rbtree and anon_vma,
475  * but it has already been inserted into prio_tree earlier.
476  */
477 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
478 {
479         struct vm_area_struct *__vma, *prev;
480         struct rb_node **rb_link, *rb_parent;
481
482         __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
483         BUG_ON(__vma && __vma->vm_start < vma->vm_end);
484         __vma_link(mm, vma, prev, rb_link, rb_parent);
485         mm->map_count++;
486 }
487
488 static inline void
489 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
490                 struct vm_area_struct *prev)
491 {
492         struct vm_area_struct *next = vma->vm_next;
493
494         prev->vm_next = next;
495         if (next)
496                 next->vm_prev = prev;
497         rb_erase(&vma->vm_rb, &mm->mm_rb);
498         if (mm->mmap_cache == vma)
499                 mm->mmap_cache = prev;
500 }
501
502 /*
503  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
504  * is already present in an i_mmap tree without adjusting the tree.
505  * The following helper function should be used when such adjustments
506  * are necessary.  The "insert" vma (if any) is to be inserted
507  * before we drop the necessary locks.
508  */
509 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
510         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
511 {
512         struct mm_struct *mm = vma->vm_mm;
513         struct vm_area_struct *next = vma->vm_next;
514         struct vm_area_struct *importer = NULL;
515         struct address_space *mapping = NULL;
516         struct prio_tree_root *root = NULL;
517         struct anon_vma *anon_vma = NULL;
518         struct file *file = vma->vm_file;
519         long adjust_next = 0;
520         int remove_next = 0;
521
522         if (next && !insert) {
523                 struct vm_area_struct *exporter = NULL;
524
525                 if (end >= next->vm_end) {
526                         /*
527                          * vma expands, overlapping all the next, and
528                          * perhaps the one after too (mprotect case 6).
529                          */
530 again:                  remove_next = 1 + (end > next->vm_end);
531                         end = next->vm_end;
532                         exporter = next;
533                         importer = vma;
534                 } else if (end > next->vm_start) {
535                         /*
536                          * vma expands, overlapping part of the next:
537                          * mprotect case 5 shifting the boundary up.
538                          */
539                         adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
540                         exporter = next;
541                         importer = vma;
542                 } else if (end < vma->vm_end) {
543                         /*
544                          * vma shrinks, and !insert tells it's not
545                          * split_vma inserting another: so it must be
546                          * mprotect case 4 shifting the boundary down.
547                          */
548                         adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
549                         exporter = vma;
550                         importer = next;
551                 }
552
553                 /*
554                  * Easily overlooked: when mprotect shifts the boundary,
555                  * make sure the expanding vma has anon_vma set if the
556                  * shrinking vma had, to cover any anon pages imported.
557                  */
558                 if (exporter && exporter->anon_vma && !importer->anon_vma) {
559                         if (anon_vma_clone(importer, exporter))
560                                 return -ENOMEM;
561                         importer->anon_vma = exporter->anon_vma;
562                 }
563         }
564
565         if (file) {
566                 mapping = file->f_mapping;
567                 if (!(vma->vm_flags & VM_NONLINEAR))
568                         root = &mapping->i_mmap;
569                 spin_lock(&mapping->i_mmap_lock);
570                 if (importer &&
571                     vma->vm_truncate_count != next->vm_truncate_count) {
572                         /*
573                          * unmap_mapping_range might be in progress:
574                          * ensure that the expanding vma is rescanned.
575                          */
576                         importer->vm_truncate_count = 0;
577                 }
578                 if (insert) {
579                         insert->vm_truncate_count = vma->vm_truncate_count;
580                         /*
581                          * Put into prio_tree now, so instantiated pages
582                          * are visible to arm/parisc __flush_dcache_page
583                          * throughout; but we cannot insert into address
584                          * space until vma start or end is updated.
585                          */
586                         __vma_link_file(insert);
587                 }
588         }
589
590         /*
591          * When changing only vma->vm_end, we don't really need anon_vma
592          * lock. This is a fairly rare case by itself, but the anon_vma
593          * lock may be shared between many sibling processes.  Skipping
594          * the lock for brk adjustments makes a difference sometimes.
595          */
596         if (vma->anon_vma && (insert || importer || start != vma->vm_start)) {
597                 anon_vma = vma->anon_vma;
598                 anon_vma_lock(anon_vma);
599         }
600
601         if (root) {
602                 flush_dcache_mmap_lock(mapping);
603                 vma_prio_tree_remove(vma, root);
604                 if (adjust_next)
605                         vma_prio_tree_remove(next, root);
606         }
607
608         vma->vm_start = start;
609         vma->vm_end = end;
610         vma->vm_pgoff = pgoff;
611         if (adjust_next) {
612                 next->vm_start += adjust_next << PAGE_SHIFT;
613                 next->vm_pgoff += adjust_next;
614         }
615
616         if (root) {
617                 if (adjust_next)
618                         vma_prio_tree_insert(next, root);
619                 vma_prio_tree_insert(vma, root);
620                 flush_dcache_mmap_unlock(mapping);
621         }
622
623         if (remove_next) {
624                 /*
625                  * vma_merge has merged next into vma, and needs
626                  * us to remove next before dropping the locks.
627                  */
628                 __vma_unlink(mm, next, vma);
629                 if (file)
630                         __remove_shared_vm_struct(next, file, mapping);
631         } else if (insert) {
632                 /*
633                  * split_vma has split insert from vma, and needs
634                  * us to insert it before dropping the locks
635                  * (it may either follow vma or precede it).
636                  */
637                 __insert_vm_struct(mm, insert);
638         }
639
640         if (anon_vma)
641                 anon_vma_unlock(anon_vma);
642         if (mapping)
643                 spin_unlock(&mapping->i_mmap_lock);
644
645         if (remove_next) {
646                 if (file) {
647                         fput(file);
648                         if (next->vm_flags & VM_EXECUTABLE)
649                                 removed_exe_file_vma(mm);
650                 }
651                 if (next->anon_vma)
652                         anon_vma_merge(vma, next);
653                 mm->map_count--;
654                 mpol_put(vma_policy(next));
655                 kmem_cache_free(vm_area_cachep, next);
656                 /*
657                  * In mprotect's case 6 (see comments on vma_merge),
658                  * we must remove another next too. It would clutter
659                  * up the code too much to do both in one go.
660                  */
661                 if (remove_next == 2) {
662                         next = vma->vm_next;
663                         goto again;
664                 }
665         }
666
667         validate_mm(mm);
668
669         return 0;
670 }
671
672 /*
673  * If the vma has a ->close operation then the driver probably needs to release
674  * per-vma resources, so we don't attempt to merge those.
675  */
676 static inline int is_mergeable_vma(struct vm_area_struct *vma,
677                         struct file *file, unsigned long vm_flags)
678 {
679         /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
680         if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
681                 return 0;
682         if (vma->vm_file != file)
683                 return 0;
684         if (vma->vm_ops && vma->vm_ops->close)
685                 return 0;
686         return 1;
687 }
688
689 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
690                                         struct anon_vma *anon_vma2)
691 {
692         return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
693 }
694
695 /*
696  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
697  * in front of (at a lower virtual address and file offset than) the vma.
698  *
699  * We cannot merge two vmas if they have differently assigned (non-NULL)
700  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
701  *
702  * We don't check here for the merged mmap wrapping around the end of pagecache
703  * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
704  * wrap, nor mmaps which cover the final page at index -1UL.
705  */
706 static int
707 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
708         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
709 {
710         if (is_mergeable_vma(vma, file, vm_flags) &&
711             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
712                 if (vma->vm_pgoff == vm_pgoff)
713                         return 1;
714         }
715         return 0;
716 }
717
718 /*
719  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
720  * beyond (at a higher virtual address and file offset than) the vma.
721  *
722  * We cannot merge two vmas if they have differently assigned (non-NULL)
723  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
724  */
725 static int
726 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
727         struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
728 {
729         if (is_mergeable_vma(vma, file, vm_flags) &&
730             is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
731                 pgoff_t vm_pglen;
732                 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
733                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
734                         return 1;
735         }
736         return 0;
737 }
738
739 /*
740  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
741  * whether that can be merged with its predecessor or its successor.
742  * Or both (it neatly fills a hole).
743  *
744  * In most cases - when called for mmap, brk or mremap - [addr,end) is
745  * certain not to be mapped by the time vma_merge is called; but when
746  * called for mprotect, it is certain to be already mapped (either at
747  * an offset within prev, or at the start of next), and the flags of
748  * this area are about to be changed to vm_flags - and the no-change
749  * case has already been eliminated.
750  *
751  * The following mprotect cases have to be considered, where AAAA is
752  * the area passed down from mprotect_fixup, never extending beyond one
753  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
754  *
755  *     AAAA             AAAA                AAAA          AAAA
756  *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
757  *    cannot merge    might become    might become    might become
758  *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
759  *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
760  *    mremap move:                                    PPPPNNNNNNNN 8
761  *        AAAA
762  *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
763  *    might become    case 1 below    case 2 below    case 3 below
764  *
765  * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
766  * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
767  */
768 struct vm_area_struct *vma_merge(struct mm_struct *mm,
769                         struct vm_area_struct *prev, unsigned long addr,
770                         unsigned long end, unsigned long vm_flags,
771                         struct anon_vma *anon_vma, struct file *file,
772                         pgoff_t pgoff, struct mempolicy *policy)
773 {
774         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
775         struct vm_area_struct *area, *next;
776         int err;
777
778         /*
779          * We later require that vma->vm_flags == vm_flags,
780          * so this tests vma->vm_flags & VM_SPECIAL, too.
781          */
782         if (vm_flags & VM_SPECIAL)
783                 return NULL;
784
785         if (prev)
786                 next = prev->vm_next;
787         else
788                 next = mm->mmap;
789         area = next;
790         if (next && next->vm_end == end)                /* cases 6, 7, 8 */
791                 next = next->vm_next;
792
793         /*
794          * Can it merge with the predecessor?
795          */
796         if (prev && prev->vm_end == addr &&
797                         mpol_equal(vma_policy(prev), policy) &&
798                         can_vma_merge_after(prev, vm_flags,
799                                                 anon_vma, file, pgoff)) {
800                 /*
801                  * OK, it can.  Can we now merge in the successor as well?
802                  */
803                 if (next && end == next->vm_start &&
804                                 mpol_equal(policy, vma_policy(next)) &&
805                                 can_vma_merge_before(next, vm_flags,
806                                         anon_vma, file, pgoff+pglen) &&
807                                 is_mergeable_anon_vma(prev->anon_vma,
808                                                       next->anon_vma)) {
809                                                         /* cases 1, 6 */
810                         err = vma_adjust(prev, prev->vm_start,
811                                 next->vm_end, prev->vm_pgoff, NULL);
812                 } else                                  /* cases 2, 5, 7 */
813                         err = vma_adjust(prev, prev->vm_start,
814                                 end, prev->vm_pgoff, NULL);
815                 if (err)
816                         return NULL;
817                 return prev;
818         }
819
820         /*
821          * Can this new request be merged in front of next?
822          */
823         if (next && end == next->vm_start &&
824                         mpol_equal(policy, vma_policy(next)) &&
825                         can_vma_merge_before(next, vm_flags,
826                                         anon_vma, file, pgoff+pglen)) {
827                 if (prev && addr < prev->vm_end)        /* case 4 */
828                         err = vma_adjust(prev, prev->vm_start,
829                                 addr, prev->vm_pgoff, NULL);
830                 else                                    /* cases 3, 8 */
831                         err = vma_adjust(area, addr, next->vm_end,
832                                 next->vm_pgoff - pglen, NULL);
833                 if (err)
834                         return NULL;
835                 return area;
836         }
837
838         return NULL;
839 }
840
841 /*
842  * Rough compatbility check to quickly see if it's even worth looking
843  * at sharing an anon_vma.
844  *
845  * They need to have the same vm_file, and the flags can only differ
846  * in things that mprotect may change.
847  *
848  * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
849  * we can merge the two vma's. For example, we refuse to merge a vma if
850  * there is a vm_ops->close() function, because that indicates that the
851  * driver is doing some kind of reference counting. But that doesn't
852  * really matter for the anon_vma sharing case.
853  */
854 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
855 {
856         return a->vm_end == b->vm_start &&
857                 mpol_equal(vma_policy(a), vma_policy(b)) &&
858                 a->vm_file == b->vm_file &&
859                 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
860                 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
861 }
862
863 /*
864  * Do some basic sanity checking to see if we can re-use the anon_vma
865  * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
866  * the same as 'old', the other will be the new one that is trying
867  * to share the anon_vma.
868  *
869  * NOTE! This runs with mm_sem held for reading, so it is possible that
870  * the anon_vma of 'old' is concurrently in the process of being set up
871  * by another page fault trying to merge _that_. But that's ok: if it
872  * is being set up, that automatically means that it will be a singleton
873  * acceptable for merging, so we can do all of this optimistically. But
874  * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
875  *
876  * IOW: that the "list_is_singular()" test on the anon_vma_chain only
877  * matters for the 'stable anon_vma' case (ie the thing we want to avoid
878  * is to return an anon_vma that is "complex" due to having gone through
879  * a fork).
880  *
881  * We also make sure that the two vma's are compatible (adjacent,
882  * and with the same memory policies). That's all stable, even with just
883  * a read lock on the mm_sem.
884  */
885 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
886 {
887         if (anon_vma_compatible(a, b)) {
888                 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
889
890                 if (anon_vma && list_is_singular(&old->anon_vma_chain))
891                         return anon_vma;
892         }
893         return NULL;
894 }
895
896 /*
897  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
898  * neighbouring vmas for a suitable anon_vma, before it goes off
899  * to allocate a new anon_vma.  It checks because a repetitive
900  * sequence of mprotects and faults may otherwise lead to distinct
901  * anon_vmas being allocated, preventing vma merge in subsequent
902  * mprotect.
903  */
904 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
905 {
906         struct anon_vma *anon_vma;
907         struct vm_area_struct *near;
908
909         near = vma->vm_next;
910         if (!near)
911                 goto try_prev;
912
913         anon_vma = reusable_anon_vma(near, vma, near);
914         if (anon_vma)
915                 return anon_vma;
916 try_prev:
917         /*
918          * It is potentially slow to have to call find_vma_prev here.
919          * But it's only on the first write fault on the vma, not
920          * every time, and we could devise a way to avoid it later
921          * (e.g. stash info in next's anon_vma_node when assigning
922          * an anon_vma, or when trying vma_merge).  Another time.
923          */
924         BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
925         if (!near)
926                 goto none;
927
928         anon_vma = reusable_anon_vma(near, near, vma);
929         if (anon_vma)
930                 return anon_vma;
931 none:
932         /*
933          * There's no absolute need to look only at touching neighbours:
934          * we could search further afield for "compatible" anon_vmas.
935          * But it would probably just be a waste of time searching,
936          * or lead to too many vmas hanging off the same anon_vma.
937          * We're trying to allow mprotect remerging later on,
938          * not trying to minimize memory used for anon_vmas.
939          */
940         return NULL;
941 }
942
943 #ifdef CONFIG_PROC_FS
944 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
945                                                 struct file *file, long pages)
946 {
947         const unsigned long stack_flags
948                 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
949
950         if (file) {
951                 mm->shared_vm += pages;
952                 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
953                         mm->exec_vm += pages;
954         } else if (flags & stack_flags)
955                 mm->stack_vm += pages;
956         if (flags & (VM_RESERVED|VM_IO))
957                 mm->reserved_vm += pages;
958 }
959 #endif /* CONFIG_PROC_FS */
960
961 /*
962  * The caller must hold down_write(&current->mm->mmap_sem).
963  */
964
965 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
966                         unsigned long len, unsigned long prot,
967                         unsigned long flags, unsigned long pgoff)
968 {
969         struct mm_struct * mm = current->mm;
970         struct inode *inode;
971         unsigned int vm_flags;
972         int error;
973         unsigned long reqprot = prot;
974
975         /*
976          * Does the application expect PROT_READ to imply PROT_EXEC?
977          *
978          * (the exception is when the underlying filesystem is noexec
979          *  mounted, in which case we dont add PROT_EXEC.)
980          */
981         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
982                 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
983                         prot |= PROT_EXEC;
984
985         if (!len)
986                 return -EINVAL;
987
988         if (!(flags & MAP_FIXED))
989                 addr = round_hint_to_min(addr);
990
991         /* Careful about overflows.. */
992         len = PAGE_ALIGN(len);
993         if (!len)
994                 return -ENOMEM;
995
996         /* offset overflow? */
997         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
998                return -EOVERFLOW;
999
1000         /* Too many mappings? */
1001         if (mm->map_count > sysctl_max_map_count)
1002                 return -ENOMEM;
1003
1004         /* Obtain the address to map to. we verify (or select) it and ensure
1005          * that it represents a valid section of the address space.
1006          */
1007         addr = get_unmapped_area(file, addr, len, pgoff, flags);
1008         if (addr & ~PAGE_MASK)
1009                 return addr;
1010
1011         /* Do simple checking here so the lower-level routines won't have
1012          * to. we assume access permissions have been handled by the open
1013          * of the memory object, so we don't do any here.
1014          */
1015         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1016                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1017
1018         if (flags & MAP_LOCKED)
1019                 if (!can_do_mlock())
1020                         return -EPERM;
1021
1022         /* mlock MCL_FUTURE? */
1023         if (vm_flags & VM_LOCKED) {
1024                 unsigned long locked, lock_limit;
1025                 locked = len >> PAGE_SHIFT;
1026                 locked += mm->locked_vm;
1027                 lock_limit = rlimit(RLIMIT_MEMLOCK);
1028                 lock_limit >>= PAGE_SHIFT;
1029                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1030                         return -EAGAIN;
1031         }
1032
1033         inode = file ? file->f_path.dentry->d_inode : NULL;
1034
1035         if (file) {
1036                 switch (flags & MAP_TYPE) {
1037                 case MAP_SHARED:
1038                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1039                                 return -EACCES;
1040
1041                         /*
1042                          * Make sure we don't allow writing to an append-only
1043                          * file..
1044                          */
1045                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1046                                 return -EACCES;
1047
1048                         /*
1049                          * Make sure there are no mandatory locks on the file.
1050                          */
1051                         if (locks_verify_locked(inode))
1052                                 return -EAGAIN;
1053
1054                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1055                         if (!(file->f_mode & FMODE_WRITE))
1056                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1057
1058                         /* fall through */
1059                 case MAP_PRIVATE:
1060                         if (!(file->f_mode & FMODE_READ))
1061                                 return -EACCES;
1062                         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1063                                 if (vm_flags & VM_EXEC)
1064                                         return -EPERM;
1065                                 vm_flags &= ~VM_MAYEXEC;
1066                         }
1067
1068                         if (!file->f_op || !file->f_op->mmap)
1069                                 return -ENODEV;
1070                         break;
1071
1072                 default:
1073                         return -EINVAL;
1074                 }
1075         } else {
1076                 switch (flags & MAP_TYPE) {
1077                 case MAP_SHARED:
1078                         /*
1079                          * Ignore pgoff.
1080                          */
1081                         pgoff = 0;
1082                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1083                         break;
1084                 case MAP_PRIVATE:
1085                         /*
1086                          * Set pgoff according to addr for anon_vma.
1087                          */
1088                         pgoff = addr >> PAGE_SHIFT;
1089                         break;
1090                 default:
1091                         return -EINVAL;
1092                 }
1093         }
1094
1095         error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1096         if (error)
1097                 return error;
1098
1099         return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1100 }
1101 EXPORT_SYMBOL(do_mmap_pgoff);
1102
1103 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1104                 unsigned long, prot, unsigned long, flags,
1105                 unsigned long, fd, unsigned long, pgoff)
1106 {
1107         struct file *file = NULL;
1108         unsigned long retval = -EBADF;
1109
1110         if (!(flags & MAP_ANONYMOUS)) {
1111                 if (unlikely(flags & MAP_HUGETLB))
1112                         return -EINVAL;
1113                 file = fget(fd);
1114                 if (!file)
1115                         goto out;
1116         } else if (flags & MAP_HUGETLB) {
1117                 struct user_struct *user = NULL;
1118                 /*
1119                  * VM_NORESERVE is used because the reservations will be
1120                  * taken when vm_ops->mmap() is called
1121                  * A dummy user value is used because we are not locking
1122                  * memory so no accounting is necessary
1123                  */
1124                 len = ALIGN(len, huge_page_size(&default_hstate));
1125                 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1126                                                 &user, HUGETLB_ANONHUGE_INODE);
1127                 if (IS_ERR(file))
1128                         return PTR_ERR(file);
1129         }
1130
1131         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1132
1133         down_write(&current->mm->mmap_sem);
1134         retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1135         up_write(&current->mm->mmap_sem);
1136
1137         if (file)
1138                 fput(file);
1139 out:
1140         return retval;
1141 }
1142
1143 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1144 struct mmap_arg_struct {
1145         unsigned long addr;
1146         unsigned long len;
1147         unsigned long prot;
1148         unsigned long flags;
1149         unsigned long fd;
1150         unsigned long offset;
1151 };
1152
1153 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1154 {
1155         struct mmap_arg_struct a;
1156
1157         if (copy_from_user(&a, arg, sizeof(a)))
1158                 return -EFAULT;
1159         if (a.offset & ~PAGE_MASK)
1160                 return -EINVAL;
1161
1162         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1163                               a.offset >> PAGE_SHIFT);
1164 }
1165 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1166
1167 /*
1168  * Some shared mappigns will want the pages marked read-only
1169  * to track write events. If so, we'll downgrade vm_page_prot
1170  * to the private version (using protection_map[] without the
1171  * VM_SHARED bit).
1172  */
1173 int vma_wants_writenotify(struct vm_area_struct *vma)
1174 {
1175         unsigned int vm_flags = vma->vm_flags;
1176
1177         /* If it was private or non-writable, the write bit is already clear */
1178         if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1179                 return 0;
1180
1181         /* The backer wishes to know when pages are first written to? */
1182         if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1183                 return 1;
1184
1185         /* The open routine did something to the protections already? */
1186         if (pgprot_val(vma->vm_page_prot) !=
1187             pgprot_val(vm_get_page_prot(vm_flags)))
1188                 return 0;
1189
1190         /* Specialty mapping? */
1191         if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1192                 return 0;
1193
1194         /* Can the mapping track the dirty pages? */
1195         return vma->vm_file && vma->vm_file->f_mapping &&
1196                 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1197 }
1198
1199 /*
1200  * We account for memory if it's a private writeable mapping,
1201  * not hugepages and VM_NORESERVE wasn't set.
1202  */
1203 static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1204 {
1205         /*
1206          * hugetlb has its own accounting separate from the core VM
1207          * VM_HUGETLB may not be set yet so we cannot check for that flag.
1208          */
1209         if (file && is_file_hugepages(file))
1210                 return 0;
1211
1212         return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1213 }
1214
1215 unsigned long mmap_region(struct file *file, unsigned long addr,
1216                           unsigned long len, unsigned long flags,
1217                           unsigned int vm_flags, unsigned long pgoff)
1218 {
1219         struct mm_struct *mm = current->mm;
1220         struct vm_area_struct *vma, *prev;
1221         int correct_wcount = 0;
1222         int error;
1223         struct rb_node **rb_link, *rb_parent;
1224         unsigned long charged = 0;
1225         struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;
1226
1227         /* Clear old maps */
1228         error = -ENOMEM;
1229 munmap_back:
1230         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1231         if (vma && vma->vm_start < addr + len) {
1232                 if (do_munmap(mm, addr, len))
1233                         return -ENOMEM;
1234                 goto munmap_back;
1235         }
1236
1237         /* Check against address space limit. */
1238         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1239                 return -ENOMEM;
1240
1241         /*
1242          * Set 'VM_NORESERVE' if we should not account for the
1243          * memory use of this mapping.
1244          */
1245         if ((flags & MAP_NORESERVE)) {
1246                 /* We honor MAP_NORESERVE if allowed to overcommit */
1247                 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1248                         vm_flags |= VM_NORESERVE;
1249
1250                 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1251                 if (file && is_file_hugepages(file))
1252                         vm_flags |= VM_NORESERVE;
1253         }
1254
1255         /*
1256          * Private writable mapping: check memory availability
1257          */
1258         if (accountable_mapping(file, vm_flags)) {
1259                 charged = len >> PAGE_SHIFT;
1260                 if (security_vm_enough_memory(charged))
1261                         return -ENOMEM;
1262                 vm_flags |= VM_ACCOUNT;
1263         }
1264
1265         /*
1266          * Can we just expand an old mapping?
1267          */
1268         vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1269         if (vma)
1270                 goto out;
1271
1272         /*
1273          * Determine the object being mapped and call the appropriate
1274          * specific mapper. the address has already been validated, but
1275          * not unmapped, but the maps are removed from the list.
1276          */
1277         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1278         if (!vma) {
1279                 error = -ENOMEM;
1280                 goto unacct_error;
1281         }
1282
1283         vma->vm_mm = mm;
1284         vma->vm_start = addr;
1285         vma->vm_end = addr + len;
1286         vma->vm_flags = vm_flags;
1287         vma->vm_page_prot = vm_get_page_prot(vm_flags);
1288         vma->vm_pgoff = pgoff;
1289         INIT_LIST_HEAD(&vma->anon_vma_chain);
1290
1291         if (file) {
1292                 error = -EINVAL;
1293                 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1294                         goto free_vma;
1295                 if (vm_flags & VM_DENYWRITE) {
1296                         error = deny_write_access(file);
1297                         if (error)
1298                                 goto free_vma;
1299                         correct_wcount = 1;
1300                 }
1301                 vma->vm_file = file;
1302                 get_file(file);
1303                 error = file->f_op->mmap(file, vma);
1304                 if (error)
1305                         goto unmap_and_free_vma;
1306                 if (vm_flags & VM_EXECUTABLE)
1307                         added_exe_file_vma(mm);
1308
1309                 /* Can addr have changed??
1310                  *
1311                  * Answer: Yes, several device drivers can do it in their
1312                  *         f_op->mmap method. -DaveM
1313                  */
1314                 addr = vma->vm_start;
1315                 pgoff = vma->vm_pgoff;
1316                 vm_flags = vma->vm_flags;
1317         } else if (vm_flags & VM_SHARED) {
1318                 error = shmem_zero_setup(vma);
1319                 if (error)
1320                         goto free_vma;
1321         }
1322
1323         if (vma_wants_writenotify(vma)) {
1324                 pgprot_t pprot = vma->vm_page_prot;
1325
1326                 /* Can vma->vm_page_prot have changed??
1327                  *
1328                  * Answer: Yes, drivers may have changed it in their
1329                  *         f_op->mmap method.
1330                  *
1331                  * Ensures that vmas marked as uncached stay that way.
1332                  */
1333                 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1334                 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1335                         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1336         }
1337
1338         vma_link(mm, vma, prev, rb_link, rb_parent);
1339         file = vma->vm_file;
1340
1341         /* Once vma denies write, undo our temporary denial count */
1342         if (correct_wcount)
1343                 atomic_inc(&inode->i_writecount);
1344 out:
1345         perf_event_mmap(vma);
1346
1347         mm->total_vm += len >> PAGE_SHIFT;
1348         vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1349         if (vm_flags & VM_LOCKED) {
1350                 if (!mlock_vma_pages_range(vma, addr, addr + len))
1351                         mm->locked_vm += (len >> PAGE_SHIFT);
1352         } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1353                 make_pages_present(addr, addr + len);
1354         return addr;
1355
1356 unmap_and_free_vma:
1357         if (correct_wcount)
1358                 atomic_inc(&inode->i_writecount);
1359         vma->vm_file = NULL;
1360         fput(file);
1361
1362         /* Undo any partial mapping done by a device driver. */
1363         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1364         charged = 0;
1365 free_vma:
1366         kmem_cache_free(vm_area_cachep, vma);
1367 unacct_error:
1368         if (charged)
1369                 vm_unacct_memory(charged);
1370         return error;
1371 }
1372
1373 /* Get an address range which is currently unmapped.
1374  * For shmat() with addr=0.
1375  *
1376  * Ugly calling convention alert:
1377  * Return value with the low bits set means error value,
1378  * ie
1379  *      if (ret & ~PAGE_MASK)
1380  *              error = ret;
1381  *
1382  * This function "knows" that -ENOMEM has the bits set.
1383  */
1384 #ifndef HAVE_ARCH_UNMAPPED_AREA
1385 unsigned long
1386 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1387                 unsigned long len, unsigned long pgoff, unsigned long flags)
1388 {
1389         struct mm_struct *mm = current->mm;
1390         struct vm_area_struct *vma;
1391         unsigned long start_addr;
1392
1393         if (len > TASK_SIZE)
1394                 return -ENOMEM;
1395
1396         if (flags & MAP_FIXED)
1397                 return addr;
1398
1399         if (addr) {
1400                 addr = PAGE_ALIGN(addr);
1401                 vma = find_vma(mm, addr);
1402                 if (TASK_SIZE - len >= addr &&
1403                     (!vma || addr + len <= vma->vm_start))
1404                         return addr;
1405         }
1406         if (len > mm->cached_hole_size) {
1407                 start_addr = addr = mm->free_area_cache;
1408         } else {
1409                 start_addr = addr = TASK_UNMAPPED_BASE;
1410                 mm->cached_hole_size = 0;
1411         }
1412
1413 full_search:
1414         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1415                 /* At this point:  (!vma || addr < vma->vm_end). */
1416                 if (TASK_SIZE - len < addr) {
1417                         /*
1418                          * Start a new search - just in case we missed
1419                          * some holes.
1420                          */
1421                         if (start_addr != TASK_UNMAPPED_BASE) {
1422                                 addr = TASK_UNMAPPED_BASE;
1423                                 start_addr = addr;
1424                                 mm->cached_hole_size = 0;
1425                                 goto full_search;
1426                         }
1427                         return -ENOMEM;
1428                 }
1429                 if (!vma || addr + len <= vma->vm_start) {
1430                         /*
1431                          * Remember the place where we stopped the search:
1432                          */
1433                         mm->free_area_cache = addr + len;
1434                         return addr;
1435                 }
1436                 if (addr + mm->cached_hole_size < vma->vm_start)
1437                         mm->cached_hole_size = vma->vm_start - addr;
1438                 addr = vma->vm_end;
1439         }
1440 }
1441 #endif  
1442
1443 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1444 {
1445         /*
1446          * Is this a new hole at the lowest possible address?
1447          */
1448         if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1449                 mm->free_area_cache = addr;
1450                 mm->cached_hole_size = ~0UL;
1451         }
1452 }
1453
1454 /*
1455  * This mmap-allocator allocates new areas top-down from below the
1456  * stack's low limit (the base):
1457  */
1458 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1459 unsigned long
1460 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1461                           const unsigned long len, const unsigned long pgoff,
1462                           const unsigned long flags)
1463 {
1464         struct vm_area_struct *vma;
1465         struct mm_struct *mm = current->mm;
1466         unsigned long addr = addr0;
1467
1468         /* requested length too big for entire address space */
1469         if (len > TASK_SIZE)
1470                 return -ENOMEM;
1471
1472         if (flags & MAP_FIXED)
1473                 return addr;
1474
1475         /* requesting a specific address */
1476         if (addr) {
1477                 addr = PAGE_ALIGN(addr);
1478                 vma = find_vma(mm, addr);
1479                 if (TASK_SIZE - len >= addr &&
1480                                 (!vma || addr + len <= vma->vm_start))
1481                         return addr;
1482         }
1483
1484         /* check if free_area_cache is useful for us */
1485         if (len <= mm->cached_hole_size) {
1486                 mm->cached_hole_size = 0;
1487                 mm->free_area_cache = mm->mmap_base;
1488         }
1489
1490         /* either no address requested or can't fit in requested address hole */
1491         addr = mm->free_area_cache;
1492
1493         /* make sure it can fit in the remaining address space */
1494         if (addr > len) {
1495                 vma = find_vma(mm, addr-len);
1496                 if (!vma || addr <= vma->vm_start)
1497                         /* remember the address as a hint for next time */
1498                         return (mm->free_area_cache = addr-len);
1499         }
1500
1501         if (mm->mmap_base < len)
1502                 goto bottomup;
1503
1504         addr = mm->mmap_base-len;
1505
1506         do {
1507                 /*
1508                  * Lookup failure means no vma is above this address,
1509                  * else if new region fits below vma->vm_start,
1510                  * return with success:
1511                  */
1512                 vma = find_vma(mm, addr);
1513                 if (!vma || addr+len <= vma->vm_start)
1514                         /* remember the address as a hint for next time */
1515                         return (mm->free_area_cache = addr);
1516
1517                 /* remember the largest hole we saw so far */
1518                 if (addr + mm->cached_hole_size < vma->vm_start)
1519                         mm->cached_hole_size = vma->vm_start - addr;
1520
1521                 /* try just below the current vma->vm_start */
1522                 addr = vma->vm_start-len;
1523         } while (len < vma->vm_start);
1524
1525 bottomup:
1526         /*
1527          * A failed mmap() very likely causes application failure,
1528          * so fall back to the bottom-up function here. This scenario
1529          * can happen with large stack limits and large mmap()
1530          * allocations.
1531          */
1532         mm->cached_hole_size = ~0UL;
1533         mm->free_area_cache = TASK_UNMAPPED_BASE;
1534         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1535         /*
1536          * Restore the topdown base:
1537          */
1538         mm->free_area_cache = mm->mmap_base;
1539         mm->cached_hole_size = ~0UL;
1540
1541         return addr;
1542 }
1543 #endif
1544
1545 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1546 {
1547         /*
1548          * Is this a new hole at the highest possible address?
1549          */
1550         if (addr > mm->free_area_cache)
1551                 mm->free_area_cache = addr;
1552
1553         /* dont allow allocations above current base */
1554         if (mm->free_area_cache > mm->mmap_base)
1555                 mm->free_area_cache = mm->mmap_base;
1556 }
1557
1558 unsigned long
1559 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1560                 unsigned long pgoff, unsigned long flags)
1561 {
1562         unsigned long (*get_area)(struct file *, unsigned long,
1563                                   unsigned long, unsigned long, unsigned long);
1564
1565         unsigned long error = arch_mmap_check(addr, len, flags);
1566         if (error)
1567                 return error;
1568
1569         /* Careful about overflows.. */
1570         if (len > TASK_SIZE)
1571                 return -ENOMEM;
1572
1573         get_area = current->mm->get_unmapped_area;
1574         if (file && file->f_op && file->f_op->get_unmapped_area)
1575                 get_area = file->f_op->get_unmapped_area;
1576         addr = get_area(file, addr, len, pgoff, flags);
1577         if (IS_ERR_VALUE(addr))
1578                 return addr;
1579
1580         if (addr > TASK_SIZE - len)
1581                 return -ENOMEM;
1582         if (addr & ~PAGE_MASK)
1583                 return -EINVAL;
1584
1585         return arch_rebalance_pgtables(addr, len);
1586 }
1587
1588 EXPORT_SYMBOL(get_unmapped_area);
1589
1590 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1591 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1592 {
1593         struct vm_area_struct *vma = NULL;
1594
1595         if (mm) {
1596                 /* Check the cache first. */
1597                 /* (Cache hit rate is typically around 35%.) */
1598                 vma = mm->mmap_cache;
1599                 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1600                         struct rb_node * rb_node;
1601
1602                         rb_node = mm->mm_rb.rb_node;
1603                         vma = NULL;
1604
1605                         while (rb_node) {
1606                                 struct vm_area_struct * vma_tmp;
1607
1608                                 vma_tmp = rb_entry(rb_node,
1609                                                 struct vm_area_struct, vm_rb);
1610
1611                                 if (vma_tmp->vm_end > addr) {
1612                                         vma = vma_tmp;
1613                                         if (vma_tmp->vm_start <= addr)
1614                                                 break;
1615                                         rb_node = rb_node->rb_left;
1616                                 } else
1617                                         rb_node = rb_node->rb_right;
1618                         }
1619                         if (vma)
1620                                 mm->mmap_cache = vma;
1621                 }
1622         }
1623         return vma;
1624 }
1625
1626 EXPORT_SYMBOL(find_vma);
1627
1628 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1629 struct vm_area_struct *
1630 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1631                         struct vm_area_struct **pprev)
1632 {
1633         struct vm_area_struct *vma = NULL, *prev = NULL;
1634         struct rb_node *rb_node;
1635         if (!mm)
1636                 goto out;
1637
1638         /* Guard against addr being lower than the first VMA */
1639         vma = mm->mmap;
1640
1641         /* Go through the RB tree quickly. */
1642         rb_node = mm->mm_rb.rb_node;
1643
1644         while (rb_node) {
1645                 struct vm_area_struct *vma_tmp;
1646                 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1647
1648                 if (addr < vma_tmp->vm_end) {
1649                         rb_node = rb_node->rb_left;
1650                 } else {
1651                         prev = vma_tmp;
1652                         if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1653                                 break;
1654                         rb_node = rb_node->rb_right;
1655                 }
1656         }
1657
1658 out:
1659         *pprev = prev;
1660         return prev ? prev->vm_next : vma;
1661 }
1662
1663 /*
1664  * Verify that the stack growth is acceptable and
1665  * update accounting. This is shared with both the
1666  * grow-up and grow-down cases.
1667  */
1668 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1669 {
1670         struct mm_struct *mm = vma->vm_mm;
1671         struct rlimit *rlim = current->signal->rlim;
1672         unsigned long new_start;
1673
1674         /* address space limit tests */
1675         if (!may_expand_vm(mm, grow))
1676                 return -ENOMEM;
1677
1678         /* Stack limit test */
1679         if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1680                 return -ENOMEM;
1681
1682         /* mlock limit tests */
1683         if (vma->vm_flags & VM_LOCKED) {
1684                 unsigned long locked;
1685                 unsigned long limit;
1686                 locked = mm->locked_vm + grow;
1687                 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1688                 limit >>= PAGE_SHIFT;
1689                 if (locked > limit && !capable(CAP_IPC_LOCK))
1690                         return -ENOMEM;
1691         }
1692
1693         /* Check to ensure the stack will not grow into a hugetlb-only region */
1694         new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1695                         vma->vm_end - size;
1696         if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1697                 return -EFAULT;
1698
1699         /*
1700          * Overcommit..  This must be the final test, as it will
1701          * update security statistics.
1702          */
1703         if (security_vm_enough_memory_mm(mm, grow))
1704                 return -ENOMEM;
1705
1706         /* Ok, everything looks good - let it rip */
1707         mm->total_vm += grow;
1708         if (vma->vm_flags & VM_LOCKED)
1709                 mm->locked_vm += grow;
1710         vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1711         return 0;
1712 }
1713
1714 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1715 /*
1716  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1717  * vma is the last one with address > vma->vm_end.  Have to extend vma.
1718  */
1719 #ifndef CONFIG_IA64
1720 static
1721 #endif
1722 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1723 {
1724         int error;
1725
1726         if (!(vma->vm_flags & VM_GROWSUP))
1727                 return -EFAULT;
1728
1729         /*
1730          * We must make sure the anon_vma is allocated
1731          * so that the anon_vma locking is not a noop.
1732          */
1733         if (unlikely(anon_vma_prepare(vma)))
1734                 return -ENOMEM;
1735         vma_lock_anon_vma(vma);
1736
1737         /*
1738          * vma->vm_start/vm_end cannot change under us because the caller
1739          * is required to hold the mmap_sem in read mode.  We need the
1740          * anon_vma lock to serialize against concurrent expand_stacks.
1741          * Also guard against wrapping around to address 0.
1742          */
1743         if (address < PAGE_ALIGN(address+4))
1744                 address = PAGE_ALIGN(address+4);
1745         else {
1746                 vma_unlock_anon_vma(vma);
1747                 return -ENOMEM;
1748         }
1749         error = 0;
1750
1751         /* Somebody else might have raced and expanded it already */
1752         if (address > vma->vm_end) {
1753                 unsigned long size, grow;
1754
1755                 size = address - vma->vm_start;
1756                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1757
1758                 error = acct_stack_growth(vma, size, grow);
1759                 if (!error) {
1760                         vma->vm_end = address;
1761                         perf_event_mmap(vma);
1762                 }
1763         }
1764         vma_unlock_anon_vma(vma);
1765         return error;
1766 }
1767 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1768
1769 /*
1770  * vma is the first one with address < vma->vm_start.  Have to extend vma.
1771  */
1772 static int expand_downwards(struct vm_area_struct *vma,
1773                                    unsigned long address)
1774 {
1775         int error;
1776
1777         /*
1778          * We must make sure the anon_vma is allocated
1779          * so that the anon_vma locking is not a noop.
1780          */
1781         if (unlikely(anon_vma_prepare(vma)))
1782                 return -ENOMEM;
1783
1784         address &= PAGE_MASK;
1785         error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1786         if (error)
1787                 return error;
1788
1789         vma_lock_anon_vma(vma);
1790
1791         /*
1792          * vma->vm_start/vm_end cannot change under us because the caller
1793          * is required to hold the mmap_sem in read mode.  We need the
1794          * anon_vma lock to serialize against concurrent expand_stacks.
1795          */
1796
1797         /* Somebody else might have raced and expanded it already */
1798         if (address < vma->vm_start) {
1799                 unsigned long size, grow;
1800
1801                 size = vma->vm_end - address;
1802                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1803
1804                 error = acct_stack_growth(vma, size, grow);
1805                 if (!error) {
1806                         vma->vm_start = address;
1807                         vma->vm_pgoff -= grow;
1808                         perf_event_mmap(vma);
1809                 }
1810         }
1811         vma_unlock_anon_vma(vma);
1812         return error;
1813 }
1814
1815 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1816 {
1817         return expand_downwards(vma, address);
1818 }
1819
1820 #ifdef CONFIG_STACK_GROWSUP
1821 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1822 {
1823         return expand_upwards(vma, address);
1824 }
1825
1826 struct vm_area_struct *
1827 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1828 {
1829         struct vm_area_struct *vma, *prev;
1830
1831         addr &= PAGE_MASK;
1832         vma = find_vma_prev(mm, addr, &prev);
1833         if (vma && (vma->vm_start <= addr))
1834                 return vma;
1835         if (!prev || expand_stack(prev, addr))
1836                 return NULL;
1837         if (prev->vm_flags & VM_LOCKED) {
1838                 mlock_vma_pages_range(prev, addr, prev->vm_end);
1839         }
1840         return prev;
1841 }
1842 #else
1843 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1844 {
1845         return expand_downwards(vma, address);
1846 }
1847
1848 struct vm_area_struct *
1849 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1850 {
1851         struct vm_area_struct * vma;
1852         unsigned long start;
1853
1854         addr &= PAGE_MASK;
1855         vma = find_vma(mm,addr);
1856         if (!vma)
1857                 return NULL;
1858         if (vma->vm_start <= addr)
1859                 return vma;
1860         if (!(vma->vm_flags & VM_GROWSDOWN))
1861                 return NULL;
1862         start = vma->vm_start;
1863         if (expand_stack(vma, addr))
1864                 return NULL;
1865         if (vma->vm_flags & VM_LOCKED) {
1866                 mlock_vma_pages_range(vma, addr, start);
1867         }
1868         return vma;
1869 }
1870 #endif
1871
1872 /*
1873  * Ok - we have the memory areas we should free on the vma list,
1874  * so release them, and do the vma updates.
1875  *
1876  * Called with the mm semaphore held.
1877  */
1878 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1879 {
1880         /* Update high watermark before we lower total_vm */
1881         update_hiwater_vm(mm);
1882         do {
1883                 long nrpages = vma_pages(vma);
1884
1885                 mm->total_vm -= nrpages;
1886                 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1887                 vma = remove_vma(vma);
1888         } while (vma);
1889         validate_mm(mm);
1890 }
1891
1892 /*
1893  * Get rid of page table information in the indicated region.
1894  *
1895  * Called with the mm semaphore held.
1896  */
1897 static void unmap_region(struct mm_struct *mm,
1898                 struct vm_area_struct *vma, struct vm_area_struct *prev,
1899                 unsigned long start, unsigned long end)
1900 {
1901         struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1902         struct mmu_gather *tlb;
1903         unsigned long nr_accounted = 0;
1904
1905         lru_add_drain();
1906         tlb = tlb_gather_mmu(mm, 0);
1907         update_hiwater_rss(mm);
1908         unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1909         vm_unacct_memory(nr_accounted);
1910         free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1911                                  next? next->vm_start: 0);
1912         tlb_finish_mmu(tlb, start, end);
1913 }
1914
1915 /*
1916  * Create a list of vma's touched by the unmap, removing them from the mm's
1917  * vma list as we go..
1918  */
1919 static void
1920 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1921         struct vm_area_struct *prev, unsigned long end)
1922 {
1923         struct vm_area_struct **insertion_point;
1924         struct vm_area_struct *tail_vma = NULL;
1925         unsigned long addr;
1926
1927         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1928         vma->vm_prev = NULL;
1929         do {
1930                 rb_erase(&vma->vm_rb, &mm->mm_rb);
1931                 mm->map_count--;
1932                 tail_vma = vma;
1933                 vma = vma->vm_next;
1934         } while (vma && vma->vm_start < end);
1935         *insertion_point = vma;
1936         if (vma)
1937                 vma->vm_prev = prev;
1938         tail_vma->vm_next = NULL;
1939         if (mm->unmap_area == arch_unmap_area)
1940                 addr = prev ? prev->vm_end : mm->mmap_base;
1941         else
1942                 addr = vma ?  vma->vm_start : mm->mmap_base;
1943         mm->unmap_area(mm, addr);
1944         mm->mmap_cache = NULL;          /* Kill the cache. */
1945 }
1946
1947 /*
1948  * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
1949  * munmap path where it doesn't make sense to fail.
1950  */
1951 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1952               unsigned long addr, int new_below)
1953 {
1954         struct mempolicy *pol;
1955         struct vm_area_struct *new;
1956         int err = -ENOMEM;
1957
1958         if (is_vm_hugetlb_page(vma) && (addr &
1959                                         ~(huge_page_mask(hstate_vma(vma)))))
1960                 return -EINVAL;
1961
1962         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1963         if (!new)
1964                 goto out_err;
1965
1966         /* most fields are the same, copy all, and then fixup */
1967         *new = *vma;
1968
1969         INIT_LIST_HEAD(&new->anon_vma_chain);
1970
1971         if (new_below)
1972                 new->vm_end = addr;
1973         else {
1974                 new->vm_start = addr;
1975                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1976         }
1977
1978         pol = mpol_dup(vma_policy(vma));
1979         if (IS_ERR(pol)) {
1980                 err = PTR_ERR(pol);
1981                 goto out_free_vma;
1982         }
1983         vma_set_policy(new, pol);
1984
1985         if (anon_vma_clone(new, vma))
1986                 goto out_free_mpol;
1987
1988         if (new->vm_file) {
1989                 get_file(new->vm_file);
1990                 if (vma->vm_flags & VM_EXECUTABLE)
1991                         added_exe_file_vma(mm);
1992         }
1993
1994         if (new->vm_ops && new->vm_ops->open)
1995                 new->vm_ops->open(new);
1996
1997         if (new_below)
1998                 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1999                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
2000         else
2001                 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2002
2003         /* Success. */
2004         if (!err)
2005                 return 0;
2006
2007         /* Clean everything up if vma_adjust failed. */
2008         if (new->vm_ops && new->vm_ops->close)
2009                 new->vm_ops->close(new);
2010         if (new->vm_file) {
2011                 if (vma->vm_flags & VM_EXECUTABLE)
2012                         removed_exe_file_vma(mm);
2013                 fput(new->vm_file);
2014         }
2015  out_free_mpol:
2016         mpol_put(pol);
2017  out_free_vma:
2018         kmem_cache_free(vm_area_cachep, new);
2019  out_err:
2020         return err;
2021 }
2022
2023 /*
2024  * Split a vma into two pieces at address 'addr', a new vma is allocated
2025  * either for the first part or the tail.
2026  */
2027 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2028               unsigned long addr, int new_below)
2029 {
2030         if (mm->map_count >= sysctl_max_map_count)
2031                 return -ENOMEM;
2032
2033         return __split_vma(mm, vma, addr, new_below);
2034 }
2035
2036 /* Munmap is split into 2 main parts -- this part which finds
2037  * what needs doing, and the areas themselves, which do the
2038  * work.  This now handles partial unmappings.
2039  * Jeremy Fitzhardinge <jeremy@goop.org>
2040  */
2041 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2042 {
2043         unsigned long end;
2044         struct vm_area_struct *vma, *prev, *last;
2045
2046         if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2047                 return -EINVAL;
2048
2049         if ((len = PAGE_ALIGN(len)) == 0)
2050                 return -EINVAL;
2051
2052         /* Find the first overlapping VMA */
2053         vma = find_vma_prev(mm, start, &prev);
2054         if (!vma)
2055                 return 0;
2056         /* we have  start < vma->vm_end  */
2057
2058         /* if it doesn't overlap, we have nothing.. */
2059         end = start + len;
2060         if (vma->vm_start >= end)
2061                 return 0;
2062
2063         /*
2064          * If we need to split any vma, do it now to save pain later.
2065          *
2066          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2067          * unmapped vm_area_struct will remain in use: so lower split_vma
2068          * places tmp vma above, and higher split_vma places tmp vma below.
2069          */
2070         if (start > vma->vm_start) {
2071                 int error;
2072
2073                 /*
2074                  * Make sure that map_count on return from munmap() will
2075                  * not exceed its limit; but let map_count go just above
2076                  * its limit temporarily, to help free resources as expected.
2077                  */
2078                 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2079                         return -ENOMEM;
2080
2081                 error = __split_vma(mm, vma, start, 0);
2082                 if (error)
2083                         return error;
2084                 prev = vma;
2085         }
2086
2087         /* Does it split the last one? */
2088         last = find_vma(mm, end);
2089         if (last && end > last->vm_start) {
2090                 int error = __split_vma(mm, last, end, 1);
2091                 if (error)
2092                         return error;
2093         }
2094         vma = prev? prev->vm_next: mm->mmap;
2095
2096         /*
2097          * unlock any mlock()ed ranges before detaching vmas
2098          */
2099         if (mm->locked_vm) {
2100                 struct vm_area_struct *tmp = vma;
2101                 while (tmp && tmp->vm_start < end) {
2102                         if (tmp->vm_flags & VM_LOCKED) {
2103                                 mm->locked_vm -= vma_pages(tmp);
2104                                 munlock_vma_pages_all(tmp);
2105                         }
2106                         tmp = tmp->vm_next;
2107                 }
2108         }
2109
2110         /*
2111          * Remove the vma's, and unmap the actual pages
2112          */
2113         detach_vmas_to_be_unmapped(mm, vma, prev, end);
2114         unmap_region(mm, vma, prev, start, end);
2115
2116         /* Fix up all other VM information */
2117         remove_vma_list(mm, vma);
2118
2119         return 0;
2120 }
2121
2122 EXPORT_SYMBOL(do_munmap);
2123
2124 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2125 {
2126         int ret;
2127         struct mm_struct *mm = current->mm;
2128
2129         profile_munmap(addr);
2130
2131         down_write(&mm->mmap_sem);
2132         ret = do_munmap(mm, addr, len);
2133         up_write(&mm->mmap_sem);
2134         return ret;
2135 }
2136
2137 static inline void verify_mm_writelocked(struct mm_struct *mm)
2138 {
2139 #ifdef CONFIG_DEBUG_VM
2140         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2141                 WARN_ON(1);
2142                 up_read(&mm->mmap_sem);
2143         }
2144 #endif
2145 }
2146
2147 /*
2148  *  this is really a simplified "do_mmap".  it only handles
2149  *  anonymous maps.  eventually we may be able to do some
2150  *  brk-specific accounting here.
2151  */
2152 unsigned long do_brk(unsigned long addr, unsigned long len)
2153 {
2154         struct mm_struct * mm = current->mm;
2155         struct vm_area_struct * vma, * prev;
2156         unsigned long flags;
2157         struct rb_node ** rb_link, * rb_parent;
2158         pgoff_t pgoff = addr >> PAGE_SHIFT;
2159         int error;
2160
2161         len = PAGE_ALIGN(len);
2162         if (!len)
2163                 return addr;
2164
2165         error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2166         if (error)
2167                 return error;
2168
2169         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2170
2171         error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2172         if (error & ~PAGE_MASK)
2173                 return error;
2174
2175         /*
2176          * mlock MCL_FUTURE?
2177          */
2178         if (mm->def_flags & VM_LOCKED) {
2179                 unsigned long locked, lock_limit;
2180                 locked = len >> PAGE_SHIFT;
2181                 locked += mm->locked_vm;
2182                 lock_limit = rlimit(RLIMIT_MEMLOCK);
2183                 lock_limit >>= PAGE_SHIFT;
2184                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2185                         return -EAGAIN;
2186         }
2187
2188         /*
2189          * mm->mmap_sem is required to protect against another thread
2190          * changing the mappings in case we sleep.
2191          */
2192         verify_mm_writelocked(mm);
2193
2194         /*
2195          * Clear old maps.  this also does some error checking for us
2196          */
2197  munmap_back:
2198         vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2199         if (vma && vma->vm_start < addr + len) {
2200                 if (do_munmap(mm, addr, len))
2201                         return -ENOMEM;
2202                 goto munmap_back;
2203         }
2204
2205         /* Check against address space limits *after* clearing old maps... */
2206         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2207                 return -ENOMEM;
2208
2209         if (mm->map_count > sysctl_max_map_count)
2210                 return -ENOMEM;
2211
2212         if (security_vm_enough_memory(len >> PAGE_SHIFT))
2213                 return -ENOMEM;
2214
2215         /* Can we just expand an old private anonymous mapping? */
2216         vma = vma_merge(mm, prev, addr, addr + len, flags,
2217                                         NULL, NULL, pgoff, NULL);
2218         if (vma)
2219                 goto out;
2220
2221         /*
2222          * create a vma struct for an anonymous mapping
2223          */
2224         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2225         if (!vma) {
2226                 vm_unacct_memory(len >> PAGE_SHIFT);
2227                 return -ENOMEM;
2228         }
2229
2230         INIT_LIST_HEAD(&vma->anon_vma_chain);
2231         vma->vm_mm = mm;
2232         vma->vm_start = addr;
2233         vma->vm_end = addr + len;
2234         vma->vm_pgoff = pgoff;
2235         vma->vm_flags = flags;
2236         vma->vm_page_prot = vm_get_page_prot(flags);
2237         vma_link(mm, vma, prev, rb_link, rb_parent);
2238 out:
2239         perf_event_mmap(vma);
2240         mm->total_vm += len >> PAGE_SHIFT;
2241         if (flags & VM_LOCKED) {
2242                 if (!mlock_vma_pages_range(vma, addr, addr + len))
2243                         mm->locked_vm += (len >> PAGE_SHIFT);
2244         }
2245         return addr;
2246 }
2247
2248 EXPORT_SYMBOL(do_brk);
2249
2250 /* Release all mmaps. */
2251 void exit_mmap(struct mm_struct *mm)
2252 {
2253         struct mmu_gather *tlb;
2254         struct vm_area_struct *vma;
2255         unsigned long nr_accounted = 0;
2256         unsigned long end;
2257
2258         /* mm's last user has gone, and its about to be pulled down */
2259         mmu_notifier_release(mm);
2260
2261         if (mm->locked_vm) {
2262                 vma = mm->mmap;
2263                 while (vma) {
2264                         if (vma->vm_flags & VM_LOCKED)
2265                                 munlock_vma_pages_all(vma);
2266                         vma = vma->vm_next;
2267                 }
2268         }
2269
2270         arch_exit_mmap(mm);
2271
2272         vma = mm->mmap;
2273         if (!vma)       /* Can happen if dup_mmap() received an OOM */
2274                 return;
2275
2276         lru_add_drain();
2277         flush_cache_mm(mm);
2278         tlb = tlb_gather_mmu(mm, 1);
2279         /* update_hiwater_rss(mm) here? but nobody should be looking */
2280         /* Use -1 here to ensure all VMAs in the mm are unmapped */
2281         end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2282         vm_unacct_memory(nr_accounted);
2283
2284         free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2285         tlb_finish_mmu(tlb, 0, end);
2286
2287         /*
2288          * Walk the list again, actually closing and freeing it,
2289          * with preemption enabled, without holding any MM locks.
2290          */
2291         while (vma)
2292                 vma = remove_vma(vma);
2293
2294         BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2295 }
2296
2297 /* Insert vm structure into process list sorted by address
2298  * and into the inode's i_mmap tree.  If vm_file is non-NULL
2299  * then i_mmap_lock is taken here.
2300  */
2301 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2302 {
2303         struct vm_area_struct * __vma, * prev;
2304         struct rb_node ** rb_link, * rb_parent;
2305
2306         /*
2307          * The vm_pgoff of a purely anonymous vma should be irrelevant
2308          * until its first write fault, when page's anon_vma and index
2309          * are set.  But now set the vm_pgoff it will almost certainly
2310          * end up with (unless mremap moves it elsewhere before that
2311          * first wfault), so /proc/pid/maps tells a consistent story.
2312          *
2313          * By setting it to reflect the virtual start address of the
2314          * vma, merges and splits can happen in a seamless way, just
2315          * using the existing file pgoff checks and manipulations.
2316          * Similarly in do_mmap_pgoff and in do_brk.
2317          */
2318         if (!vma->vm_file) {
2319                 BUG_ON(vma->anon_vma);
2320                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2321         }
2322         __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2323         if (__vma && __vma->vm_start < vma->vm_end)
2324                 return -ENOMEM;
2325         if ((vma->vm_flags & VM_ACCOUNT) &&
2326              security_vm_enough_memory_mm(mm, vma_pages(vma)))
2327                 return -ENOMEM;
2328         vma_link(mm, vma, prev, rb_link, rb_parent);
2329         return 0;
2330 }
2331
2332 /*
2333  * Copy the vma structure to a new location in the same mm,
2334  * prior to moving page table entries, to effect an mremap move.
2335  */
2336 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2337         unsigned long addr, unsigned long len, pgoff_t pgoff)
2338 {
2339         struct vm_area_struct *vma = *vmap;
2340         unsigned long vma_start = vma->vm_start;
2341         struct mm_struct *mm = vma->vm_mm;
2342         struct vm_area_struct *new_vma, *prev;
2343         struct rb_node **rb_link, *rb_parent;
2344         struct mempolicy *pol;
2345
2346         /*
2347          * If anonymous vma has not yet been faulted, update new pgoff
2348          * to match new location, to increase its chance of merging.
2349          */
2350         if (!vma->vm_file && !vma->anon_vma)
2351                 pgoff = addr >> PAGE_SHIFT;
2352
2353         find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2354         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2355                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2356         if (new_vma) {
2357                 /*
2358                  * Source vma may have been merged into new_vma
2359                  */
2360                 if (vma_start >= new_vma->vm_start &&
2361                     vma_start < new_vma->vm_end)
2362                         *vmap = new_vma;
2363         } else {
2364                 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2365                 if (new_vma) {
2366                         *new_vma = *vma;
2367                         pol = mpol_dup(vma_policy(vma));
2368                         if (IS_ERR(pol))
2369                                 goto out_free_vma;
2370                         INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2371                         if (anon_vma_clone(new_vma, vma))
2372                                 goto out_free_mempol;
2373                         vma_set_policy(new_vma, pol);
2374                         new_vma->vm_start = addr;
2375                         new_vma->vm_end = addr + len;
2376                         new_vma->vm_pgoff = pgoff;
2377                         if (new_vma->vm_file) {
2378                                 get_file(new_vma->vm_file);
2379                                 if (vma->vm_flags & VM_EXECUTABLE)
2380                                         added_exe_file_vma(mm);
2381                         }
2382                         if (new_vma->vm_ops && new_vma->vm_ops->open)
2383                                 new_vma->vm_ops->open(new_vma);
2384                         vma_link(mm, new_vma, prev, rb_link, rb_parent);
2385                 }
2386         }
2387         return new_vma;
2388
2389  out_free_mempol:
2390         mpol_put(pol);
2391  out_free_vma:
2392         kmem_cache_free(vm_area_cachep, new_vma);
2393         return NULL;
2394 }
2395
2396 /*
2397  * Return true if the calling process may expand its vm space by the passed
2398  * number of pages
2399  */
2400 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2401 {
2402         unsigned long cur = mm->total_vm;       /* pages */
2403         unsigned long lim;
2404
2405         lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2406
2407         if (cur + npages > lim)
2408                 return 0;
2409         return 1;
2410 }
2411
2412
2413 static int special_mapping_fault(struct vm_area_struct *vma,
2414                                 struct vm_fault *vmf)
2415 {
2416         pgoff_t pgoff;
2417         struct page **pages;
2418
2419         /*
2420          * special mappings have no vm_file, and in that case, the mm
2421          * uses vm_pgoff internally. So we have to subtract it from here.
2422          * We are allowed to do this because we are the mm; do not copy
2423          * this code into drivers!
2424          */
2425         pgoff = vmf->pgoff - vma->vm_pgoff;
2426
2427         for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2428                 pgoff--;
2429
2430         if (*pages) {
2431                 struct page *page = *pages;
2432                 get_page(page);
2433                 vmf->page = page;
2434                 return 0;
2435         }
2436
2437         return VM_FAULT_SIGBUS;
2438 }
2439
2440 /*
2441  * Having a close hook prevents vma merging regardless of flags.
2442  */
2443 static void special_mapping_close(struct vm_area_struct *vma)
2444 {
2445 }
2446
2447 static const struct vm_operations_struct special_mapping_vmops = {
2448         .close = special_mapping_close,
2449         .fault = special_mapping_fault,
2450 };
2451
2452 /*
2453  * Called with mm->mmap_sem held for writing.
2454  * Insert a new vma covering the given region, with the given flags.
2455  * Its pages are supplied by the given array of struct page *.
2456  * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2457  * The region past the last page supplied will always produce SIGBUS.
2458  * The array pointer and the pages it points to are assumed to stay alive
2459  * for as long as this mapping might exist.
2460  */
2461 int install_special_mapping(struct mm_struct *mm,
2462                             unsigned long addr, unsigned long len,
2463                             unsigned long vm_flags, struct page **pages)
2464 {
2465         struct vm_area_struct *vma;
2466
2467         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2468         if (unlikely(vma == NULL))
2469                 return -ENOMEM;
2470
2471         INIT_LIST_HEAD(&vma->anon_vma_chain);
2472         vma->vm_mm = mm;
2473         vma->vm_start = addr;
2474         vma->vm_end = addr + len;
2475
2476         vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2477         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2478
2479         vma->vm_ops = &special_mapping_vmops;
2480         vma->vm_private_data = pages;
2481
2482         if (unlikely(insert_vm_struct(mm, vma))) {
2483                 kmem_cache_free(vm_area_cachep, vma);
2484                 return -ENOMEM;
2485         }
2486
2487         mm->total_vm += len >> PAGE_SHIFT;
2488
2489         perf_event_mmap(vma);
2490
2491         return 0;
2492 }
2493
2494 static DEFINE_MUTEX(mm_all_locks_mutex);
2495
2496 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2497 {
2498         if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2499                 /*
2500                  * The LSB of head.next can't change from under us
2501                  * because we hold the mm_all_locks_mutex.
2502                  */
2503                 spin_lock_nest_lock(&anon_vma->root->lock, &mm->mmap_sem);
2504                 /*
2505                  * We can safely modify head.next after taking the
2506                  * anon_vma->root->lock. If some other vma in this mm shares
2507                  * the same anon_vma we won't take it again.
2508                  *
2509                  * No need of atomic instructions here, head.next
2510                  * can't change from under us thanks to the
2511                  * anon_vma->root->lock.
2512                  */
2513                 if (__test_and_set_bit(0, (unsigned long *)
2514                                        &anon_vma->root->head.next))
2515                         BUG();
2516         }
2517 }
2518
2519 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2520 {
2521         if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2522                 /*
2523                  * AS_MM_ALL_LOCKS can't change from under us because
2524                  * we hold the mm_all_locks_mutex.
2525                  *
2526                  * Operations on ->flags have to be atomic because
2527                  * even if AS_MM_ALL_LOCKS is stable thanks to the
2528                  * mm_all_locks_mutex, there may be other cpus
2529                  * changing other bitflags in parallel to us.
2530                  */
2531                 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2532                         BUG();
2533                 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2534         }
2535 }
2536
2537 /*
2538  * This operation locks against the VM for all pte/vma/mm related
2539  * operations that could ever happen on a certain mm. This includes
2540  * vmtruncate, try_to_unmap, and all page faults.
2541  *
2542  * The caller must take the mmap_sem in write mode before calling
2543  * mm_take_all_locks(). The caller isn't allowed to release the
2544  * mmap_sem until mm_drop_all_locks() returns.
2545  *
2546  * mmap_sem in write mode is required in order to block all operations
2547  * that could modify pagetables and free pages without need of
2548  * altering the vma layout (for example populate_range() with
2549  * nonlinear vmas). It's also needed in write mode to avoid new
2550  * anon_vmas to be associated with existing vmas.
2551  *
2552  * A single task can't take more than one mm_take_all_locks() in a row
2553  * or it would deadlock.
2554  *
2555  * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2556  * mapping->flags avoid to take the same lock twice, if more than one
2557  * vma in this mm is backed by the same anon_vma or address_space.
2558  *
2559  * We can take all the locks in random order because the VM code
2560  * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2561  * takes more than one of them in a row. Secondly we're protected
2562  * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2563  *
2564  * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2565  * that may have to take thousand of locks.
2566  *
2567  * mm_take_all_locks() can fail if it's interrupted by signals.
2568  */
2569 int mm_take_all_locks(struct mm_struct *mm)
2570 {
2571         struct vm_area_struct *vma;
2572         struct anon_vma_chain *avc;
2573         int ret = -EINTR;
2574
2575         BUG_ON(down_read_trylock(&mm->mmap_sem));
2576
2577         mutex_lock(&mm_all_locks_mutex);
2578
2579         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2580                 if (signal_pending(current))
2581                         goto out_unlock;
2582                 if (vma->vm_file && vma->vm_file->f_mapping)
2583                         vm_lock_mapping(mm, vma->vm_file->f_mapping);
2584         }
2585
2586         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2587                 if (signal_pending(current))
2588                         goto out_unlock;
2589                 if (vma->anon_vma)
2590                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2591                                 vm_lock_anon_vma(mm, avc->anon_vma);
2592         }
2593
2594         ret = 0;
2595
2596 out_unlock:
2597         if (ret)
2598                 mm_drop_all_locks(mm);
2599
2600         return ret;
2601 }
2602
2603 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2604 {
2605         if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2606                 /*
2607                  * The LSB of head.next can't change to 0 from under
2608                  * us because we hold the mm_all_locks_mutex.
2609                  *
2610                  * We must however clear the bitflag before unlocking
2611                  * the vma so the users using the anon_vma->head will
2612                  * never see our bitflag.
2613                  *
2614                  * No need of atomic instructions here, head.next
2615                  * can't change from under us until we release the
2616                  * anon_vma->root->lock.
2617                  */
2618                 if (!__test_and_clear_bit(0, (unsigned long *)
2619                                           &anon_vma->root->head.next))
2620                         BUG();
2621                 anon_vma_unlock(anon_vma);
2622         }
2623 }
2624
2625 static void vm_unlock_mapping(struct address_space *mapping)
2626 {
2627         if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2628                 /*
2629                  * AS_MM_ALL_LOCKS can't change to 0 from under us
2630                  * because we hold the mm_all_locks_mutex.
2631                  */
2632                 spin_unlock(&mapping->i_mmap_lock);
2633                 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2634                                         &mapping->flags))
2635                         BUG();
2636         }
2637 }
2638
2639 /*
2640  * The mmap_sem cannot be released by the caller until
2641  * mm_drop_all_locks() returns.
2642  */
2643 void mm_drop_all_locks(struct mm_struct *mm)
2644 {
2645         struct vm_area_struct *vma;
2646         struct anon_vma_chain *avc;
2647
2648         BUG_ON(down_read_trylock(&mm->mmap_sem));
2649         BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2650
2651         for (vma = mm->mmap; vma; vma = vma->vm_next) {
2652                 if (vma->anon_vma)
2653                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2654                                 vm_unlock_anon_vma(avc->anon_vma);
2655                 if (vma->vm_file && vma->vm_file->f_mapping)
2656                         vm_unlock_mapping(vma->vm_file->f_mapping);
2657         }
2658
2659         mutex_unlock(&mm_all_locks_mutex);
2660 }
2661
2662 /*
2663  * initialise the VMA slab
2664  */
2665 void __init mmap_init(void)
2666 {
2667         int ret;
2668
2669         ret = percpu_counter_init(&vm_committed_as, 0);
2670         VM_BUG_ON(ret);
2671 }